1. Technical Field
The present disclosure relates to a display apparatus, a lighting control circuit, and a method of driving lighting of a display apparatus.
2. Description of Related Art
Nowadays, a display unit using light emitting diodes (LEDs) as light emitting elements and a display apparatus using the display unit are manufactured. For example, combining a plurality of display units allows for obtaining a large-size display apparatus. In a display unit including LEDs arranged in an m row by n column dot matrix array, for example, anode terminals of LEDs at each row are connected to a single common line, and cathode terminals of LEDs at each column are connected to a single drive line. Then, the m-rows of common lines are successively turned ON at a predetermined cycle, and the LEDs disposed on the turned-ON common lines are individually driven by the drive lines.
In order to display an image by such display unit, conventionally, a frame, which is a single unit for displaying one image, is divided into a plurality of subframes. In such dividing of a frame into subframes, while the same data (i.e., same brightness) is typically used in all subframes, brightness is varied in each subframe to display an image with multi-gradation (see JP 2010-054989 A). In this specification, displaying images with such multi-gradation using subframes is referred to as “subframe modulation”.
In such subframe modulation, in order to increase the number of gradations, the subframes whose number corresponding to the number of gradations are required. However, the frame cycle, which is the cycle of updating image, is defined by each display unit, for example, to be 15 Hz, 30 Hz, 60 Hz or the like. Accordingly, in dividing one frame into a plurality of subframes, faster operation is required as the number of subframes increases. Therefore, in order to increase the number of gradations by subframe modulation, the hardware specification corresponding to the fast operations is required, resulting in a complicated structure and increased cost of the display apparatus. Accordingly, in a display unit to be driven at a small duty ratio of dynamic driving (e.g., 1/24 duty, 1/32 duty or the like) in relatively short subframe cycles, it is not easy to increase the number of gradations, i.e., the number of subframes.